Hydraulic press



w. ERNST ET AL HYDRAULIC PRESS Filed April 11, 195o Feb.- 23,1933.

Patented Feb. 2s, 1933 UNITED STATES PATENT OFFICE WALTER naNsT, HOwAnnF. nAcmrLLrN, AND naman. THOnEsoN, OF MOUNT amm, omO,1Ass1eNons To THEHYDRAULIC PRESS MANUFACTURING COMPANY. or

MOUNT GILEAD, OHIO nYnnAULIo Pnl-:ss

Application led April 11, 1930. Serial No. 443,488.

Our invention relates to hydraulic presses and more particularly tohydraulic circuits and associated valve mechanism for operatingsuch=presses.

5 It is desirable that the resses which are used for continuousoperation for the pressing of a large number of pieces ofl work beoperated rapidly. It is necessary that regardless of the speed ofoperation, certain l0 predetermined high pressures be employed duringthe final part of the pressing stroke of the platen or other tool. Inorder to obtain l high operatin speed without sacrificing the final highwor ing pressure various forms of l5 presses and press operatingcircuits have been provided which in eneral include a main pressingcylinder o relatively lar e diameter which is employed for effecting t efinall rt of each pressing stroke, a booster t0 cylindmr or cylinderslof relatively small diameter for driving the platen during the lirstpart of the pressing stroke, and .a platen re-` turning cylinder orcylinders of small diameter for effecting rapid return ofi the l5 platenafter a pressing stroke has been completed. Itisapparent that since thebooster and platen returning cylinders are employed for only what may betermed light operation o the press, it is not necessary that the 0 Huidsupplied to these cylinders be of as high pressure asA is usuallyrequired for the 4main pressing cylinder. v f

In accordance with our invention Vwe provide a press having a maincylinder, and

5 auxiliary cylinders servingfboth as booster cylinders and as platenreturning or retractving cylinders. a source of low pressure iiuidpressure, hydraulic connections forming a [high pressure circuit withthe main cylinder 0 and the high pressure source and also vforming a lowpressure hydraulic circuit with the auxiliary cylinder and the lowpressure source. We further provide valve means in said circuits 'for'controlling the application 5 ofhigh pressure fluid to'the main cylinderand the admission of low pressure fluid to the respective ends of theauxiliary cylinders.

The main` object of' our invention is to provide a hydraulic press andhydraulic means for the Operation thereof together embodying theprincipal features outlinedv above .and also further novelfeaturesjwhich will become apparent from a reading of the Afollowingdetailedv description, the appended claims and the several viewsillustrated in the drawin in which: l

Figure 1 1s a vertical sectional view of certain parts of the pressembodying our invention; and showing in diagrammatic form low and highpressure circuits for operating the press,certain valves being shown insecj tion and the several parts being shown in the positions they willoccupy during the first part of a pressing stroke;

' Figure 2 is a sectional view of a surge shifting'valve showing itsposition during the final partofa pressing stroke;

. Figure -3 is a sectional view of a control valve showing the ositionit will occupy during a return strole of the platen, and 70 FigureI 4 isa sectional view of a .modified form of surge shifting valve.

The illustrative embodiment of our inven tion shown in the drawinincludes a press A, a` hi h pressure pum a low pressure 3pump' and asurge tan .D mounted at the to of the press. v

he press A includes a main cylinder 1, a reciprocatory ram 2 therein, aLplaten 3 fastened to the lower end of the ram, two auxiliary cylinders 44 each having'a double act-v ingpiston 5 mounted for reciprocationtherein and connected to the platen 3 by means ofva piston rod 6.

As stated above the working, or final part 86 of each ressing stroke isperformed by the ram 2. he cylinders 4 are termed auxiliary cylindersfor the reason that they serve to position the laten -in pressingrelation` to the workbe ore`` final pressing and to re- 90 auxiliarcylinder and for. admitting such.

fluid be ow the pistons to the lower or r e tracting end 8of eachcylinder. In the 1llustrative embodiment of our invention, the

means for admitting pressure fluid to therespective ends of theauxiliary cylinders include connections between the low pressure pump-Cand both ends of the auxiliary cylinders, which connections form a lowpressure hydraulic circuit with the surge tank, the

-auxiliary cylinders and the pump. These connections include a pumpintake pipe 9 communicating a-t one of its ends with the surge tank andhaving a branch connection 10 at its other end which communicates withthe pump, a low pressure delivery pipe 11 connected to the pump outletand also to a control valve 12 which is adapted to direct low pressure14 respectively. The particucylinders to which directed is deterpipes 13and lar end of the auxiliary the low pressure fluid isv mined by theposition of the control valve.

The control valve-is preferably of the balanced piston or spool type andin the form shown includes a valve casing 15 provided with a valvechamber 16 and a piston valve 17 mounted' for sliding movement in thechamber and .including spaced heads 18, 19-

and 20 and reduced connecting portions 21 and 22. The piston valve isprovided with a longitudinally extending passage 23 which communicatesdirectly with the valve chamber at the upper end thereofas viewed inthe.

drawing and which also communicates with the chamber at the .lower endthereof by means of a diagonal passage-24 extending through the head 18,the passages 23 and 24 providing constant communication between theopposite ends of the valve chamber, and thus maintaining balancedpressures at the ends of the valve 17 facilitating the shifting of thelatter. Lateral passages 25-25 provide communication between thelongitudinal passage 23 and the chamber at a point between the heads 18and 19 of the valve.

The llow pressure delivery pipe communi- Cates with the valve chamber 16at a point intermediate the opposite ends thereof but somewhat closer tothe upper end as viewed in the drawing, and the auxiliary pipes 13 and14 communicate withV the chamber at i points respectively below andabove the pipe It will be observed that when the piston valve 17 is inthe Figure 1 position, low pressure'fluid delivered through the pipe 11will pass into the valve chamber between the valve fluid from the pumpto either the booster end 7 or the retractinflr end 8 of each auxiliarycylinder by means of auxiliary `iary pipe sages 25 and 23 in the pistonvalve, and the above the valve head 2O and an exhaust pipe 26, one endof which communicates with the chamber at itsextreme upper end and theother end of which/communicates with-the surge tank. Low pressure fluidbeing directed to thev booster ends of the auxiliary cylinders will movethe pistons 5, 5 and consequently the ram 2 downwardly to initiate vapressing stroke. Fluid containedin the retracting ends of return to thesurge tank through the pipe 14, that portion of the valve chamber whlchis above the valve head 20, and the exhaust pipe 26. When thel pistonvalve 17 is moved to its Fi ure 3 position .the low pressure Huid willbe irected to the retracting ends of the auxiliary cylinders by way ofthe low pressure delivery pipe 11, the valve chamber 16 and the pipe 14.At this time the pistons 5 and the ram will be moved upwardly and thefluid contained in the booster ends of the auxiliary cylinders will bereturned to the surge tank through the medium of the auxil- 13, thevalve chamber 16, the pasexhaust pipe 26.

In order that the low pressure pump may be run continuously duringintervals between operatino' strokes of the platen we have provided a owpressure by-pass pipe 27 communicating at one of its ends with the lowpressure delivery pipe` 11 and at its other end with the exhaust pipe26, and a pressure operated by-pass valve 28 interposed in the bypass.pipe. This valve may be of any suitable and well-known form of pressureoperated by-pass or relief valve.

For operating the piston valve 17 to control the movements of the ramand associated parts, we provide the valve with a stem 29extendingthrough the bottom of the valve casing and pivotally connectedas at 30 to a treadle 31 fulcrumed as at 32 on a fixed bracket 33. Aspring 34 interposed between the treadle and thevalve casing serves tonoru mally maintain the valve in its Figure 3 position. v

Hydraulic connections provided between themain cylinder, the surge tankand the high pressure pump form a high pressure hydraulic circuit withthe afore-named elements. This high pressure circuit includes the pumpintake pipe 9 which it will be seen supplies fluid to both pumps, abranch pipe 35 connecting the pump intake pipe to the pump. and a highpressure delivery pipe 36 which is connected at one of its ends to ,thedischarge side of thepump and at its other end is conthe auxiliarycylinders will y with the cavit therein. A surge shifting valve37, to beater described, normally provides communication between the maincylinder and the surge tank and is adapted to 5 cut off communicationtherebetween to -thus confine the discharge from the high pressure pumpto the main cylinder. The high ressure circuit also preferably includesa igh pressure branch plpe 38 which communicates 510 at one of its endswith the pipe 36 and at its other end communicates with the valvechamber of the control valve 12 at a point below the pi 13. The exhaustpipe 26 hereinbefore dieescribed as forming part 'of the low 15'pressure circuit also forms a part of the high pressure circuit. Whenthe piston valve 17 of the control valve is in the Figure 1 position,the valvehead 19 covers the end of the pipe 38 so that high pressurefluid is prevented 20 from flowing through the high, pressure branchpipe 3 8 and the entiredischarge of' the high pressure pump is directed-to .the surge shifting valve. When thepiston valve is in the Figure v3position, fluid will flow from the high pressure pump through thepipes'36 and 38, the valve chamber 16 between l the heads 18 and 19 ofthe piston valve, the passages 25 and 23 in the valve and the exhaustpipe 26, being thereby returned to the surge tank.

It is desirable lthat when the platen encounters resistance to itsdownward travel resulting in a building up of pressure in the. auxiliarycylinder and the low pressure circuit, the

'35 main cylinder be shut off from communication with the surge tank sothat the discharge of the high pressure pump will be confined to themain cylinder for completing the pressing stroke. This function isaccomplished 40 by the surge shifting valve which includes a valvecasing 41 and valve chamber 42 therein, a port 43 affording constantcommunication between the valve chamber and the main cylinder anda port44 adapted to afford communicatiop between the surge tank and the valvechamber. A piston valve 45, having spaced heads 46 and 47 and 'a,connecting stem 48 is mounted for sliding movements in the valvechamber. Means are provided for urging the valve to the right,\saidmeans preferably comprising a spring 49 interposed between the v alvehead 46 undone end of the valve casing and tending to hold the valve inits Figure 1 or open position.- When the valve has been moved to itsFigure 2 position, the spring serves to move the valve from the Figure 2position lto the Figure `lposition, thus constituting valve o eningmeans. A vent opening'50 in the val) the valve head 46 and the adjacentend of the casing provides for free shifting of the valve.

It willbe observedthat when the valve 45V is in its Figure 1 positionthe main cylinder, the high pressure pump andthe surge tank G5 are allin communication each with theothers,

ve casing between and that when the valve is moved to the left to itsFigure 2 position the head 47 will cut ofi' communication ,betweenthevsurge tank and the cylinder so that the discharge side of the highpressure pump will communicate with the main cylinder only.

For automatically moving the piston valve 45 from its Figure 1 positionto its Figure 2 position when' the pressure builds up in the lowpressure circuit, we have provided the valve with a stem 51\whichextends into a pressure chamber 52 formed in the valve casrlng, and abranch pipe connection 53 affording constant communication between thepressure chamber and the pipe 13. When the platen encounters resistanceto its pressingstrokeand the pressure builds up in the low pressurecircuit to a predetermined extent dependent upon the constant of thespring 49, the pressure acting upon the stem 51 will move the pistonvalve Vto its Figure 2 position whereupon the pressing stroke will becompleted in the manner described above.

In some cases, particularly in large presses l of heavy constructlon, itmay be desirable tov use pressure actuated means for moving the v piston valve 45 t0 its Figure 1 or open position. The modified form ofsurge shifting valve shown in Figure 4 is provided wit-h such meanswhich comprises a plunger 51a extendingfrom the valve head 46 into apressure chamber 52 in the left hand end of the valve casing, thechamber 52l1 being in con- Y stant communication with the i'etractingends of the auxiliary cylinders through the medium of a pipe 53".VPreferably the plunger 5la is of somewhat larger diameter than theplunger 51 so that when the platen and ram are performing the first partof a pressing stroke, the back pressure in the retracting ends of theauxiliary cylinders, which pres sure is due to the somewhat restrictedexhaust opening, will 'be sufiicient to maintain the piston valve 45 inits Figure 1 position.l When auxiliaryv III pressing stroke, we providethe high pressure delivery pipe with anormally c osed pressure-operatedvalve 53 having an exhaust plpe 53b connecting the valve'to the surgetank and adapted to open when a4 predeteri mined pressure has beenreachedA in the main cylinder 1 to thus place the delivery pipe in acommunication with the surge tank. This valve serves as a safety valveas well as a pres- 4lowed to overtravel there might result the breakingof the piston rods 6, since if the work being pressed does notsufliciently resist the pressure exerted by the ram, the pistons 5 willcontact with the bottoms of the auxiliary cylinders so that the pistonrods will have to bear the strain of the full working pressure of theram minus the slight resistance offered 'by the work. To prevent suchinjury to the press we provide branch pipes 54 which respectivelycommunicate at one end with the lower ends of the .auxiliary cylindersbetween the-pipes 14 and thebooster ends of the cylinders at their otherends communicate with the pipe 14, and check valves 55-55, one in v eachof said branches. The cheek valves are arranged to permit flow'of fluidfrom the booster ends of the cylinders to the pipe 14 when the upperedges of the pistons 5 have passed below the branches '54, but tovprevent fiow of fluid in the opposite direction. If the resistanceoffered by the work is insufficient to arrest the movement of the platenand the ram, the latter and the pistons 5-5 will descend until the upperedges of the pistons have passed below the branches 54 after which fluidwill pass from4 the booster ends of the auxiliary cylinder through thepipe 14, the valve chamber 16, and the exhaust pipe 26, therebyreturning to the surge tank. This will relieve the pressure in the lowpressure circuit and also in the chamber 52 of the surge shifting valve,so that the spring 49 will return the piston valve to its Figure lposition and further downward movement of the ram will be prevented. i,

The operation of the press 1s as follows.

` It will be assumed that the parts are in the A' will be in its Figure3 position when the relative positions shown in Figure 1,' with theexception of the piston*y valve 17 which platen isl at rest in itsuppermost position.

To cause a pressing stroke to be performed, -the tread'e 31 isdepressed, thus moving the piston valve to its Figure 1 position. The

' low pressure pump will then deliver low presfas sure fluid to thebooster ends of theauxiliary cylinders by way of the pipe 11, the valvechamber 16,. and the pipe 13, and the low pressure fluid acting upon theupper edges of the pistons 5 willi then initiate a pressing stroke ofthe platen. At this time the high pressure branch pipe 38 is cut olffrom communication with the exhaust pipe 26 bymeans ofthe valve head 19in the control valve, and the high pressure pump discharge will flowinto the main cylinder to prefill the latter in conjunction `with fluidentering the cylinder directly from the surge tank by way of port platenencounters resistance to its downward travel pressure will build upon inthe low pressure circuit and in the pressure cham- ,ber 52, therebyshifting the piston valve 45 of the surge shifting valve to its Figure 3position so that the main cylinder will communicate with the highpressure pump only, and the pressing stroke will be completed. After thecomp;.etion of the pressing stroke the treadle 31 is' released and thespring 34wi1l return the piston valve 17to its Flgure 3 position. Thiswill relieve the pressure in the booster ends `of the auxiliary cylinderand also the pressure in the chamber 52 so that the piston valve 45 ofthe surge shifting valve will be returned to the Figure 1 position, 1nl

between the main cylinder and `the surge '.tank. The retracting `ends ofthe auxiliary cylinders will simultaneously be placed in communicationwith the low pressure delivery pipe through the medium of the valvechamber 16 and the pipe 14 and the platen and ram will be returned totheir upper positions'. When the pistons 5 have passed above the pipes13 iiuid will be trapped in the booster ends of the auxiliary cylindersand the by-pass valve 28 will automatically open so that the `dischargeof the low pressure pump will be returned to the surge tank by means ofthe by-pass pipe 27 and the exhaust pipe 26. The various parts will thenremain in the last-named positionsuntil the treadle 31 is againvdepressed at which time another cycle will be performed inthe samemanner communicate with an exhaust; a source of low pressure fluidpressure; a low pressure delivery pipe in communication with said lowpressuresource; separate 1o.v pressure auxiliary pipes respectivelycommunicating with said auxiliary cylinder at the opposite ends thereof;and valve means in said high pressure branch pipe for controllingcommunication of said high pressure source with said exhaust, andinterposed between said low pressure delivery pipe and said low pressureauxiliary pipes for controlling admission of the low pressure fluidseparately to the respective ends of the auxiliary cylinder to effectreciprocations of said ram. i

2. The combination with a hydraulic press including a main cylinder, areciprocatory lao ram therein, an auxiliary cylinder and a pistontherein and having connection with said ram; of a surge tank; a highpressure ump;

means forming a high pressure hydrau ic circuit with said surge tank,said main cylinder vand said pump and affording constant communicationof said `maincylinder with saidA pump; a low pressure pump; meansforming a vlow pressure hydraulic circuit with both ends of saidauxiliary cylinder and said low pressure pump; a surge shifting valve insaid igh4 pressure c1rcu1t normally 1n an open position affordingcommunication vbetween vsaid main cylinder and said surge tank, and

movable to cut ofi' communication therebetween; means operable duringthe pressing stroke of the ram to move said surge shifting valve to itsclosed position to complete the pressing stroke; and a control valveinterposed in said high and low pressure circuits for first directinglowpressure fluid to one end of said auxiliary cylinder to initiate thepressing stroke of the ram, and for then directing low pressure fluid tothe otherv end of said auxiliary cylinder for effecting a return strokeof the ram.

\ 3. The combination with a hydraulic press including a main cylinder, areciprocatory ram therein,\ an auxiliary cylinder and a piston thereinand having connection with said ram; of a surge tank; a high pressurepump; means forming a high pressure hydraulic circuit withl said surgetank, said main cylinder and saidpump and including means pro'- vidingconstant communication between said main cylinder and said pump; a lowpressure pump; ,means forming a low pressure hydrauliccircuit with bothends of said auxiliary cylinder and said low pressure pump; a surgeshifting valve in said high pressure circuit normally i an-open positionaffording communication between said main cylinder and said surge tank,and movable to cut 0E communication therebetween; pres-v sureresponsive-means having hydraulic con- A nection with said low pressure circuitand operable upon a building up of pressure therein during a pressingstroke of the ram to move said surge shifting valve to its closedposition to complete the pressing stroke; and a cont-rol valveinterposed in said high and low pressure circuits for first directinglow pressure fluid to one end of said auxiliaryl cylinder to initiatethe pressing stroke of the ram, and for then directing low pressurefluid to the other end of said auxiliary cylinder for effecting a returnstroke of the ram. A

4. The combination with a hydraulic press including a main cylinder, areciprocatory y ram therein, an auxiliary cylinderv having e booster andretractingends; and a piston therein and havingl. connection with `said1 ram; of arsource of gh ressure fluid ressure; a high pressure de1veryp1pe a ordling constant communication between said source andsaidmam cyhnder; a source of low pressure fluid pressure; 'a lowl ressuredelivery pipe in communication with said low pressure source; a lowpressure auxiliary pipe communicatin with the booster end of saidauxiliary cylinder; a second low pressure auxiliary pi e communicatingwith said. auxiliary cylin er adj acentto the retracting end thereof;valve means interposed `between said low pressure delivery pipe andsaidilowaressure aux1liary pipes or controlling a sion of the lowpressure fluid separately to the respective ends of the auxiliarycylinder toeflectreciprocations of said ram; a relief mispipecommunicating at one -of its ends with said auxiliary cylinder adjacentto said second low pressure auxiliary pipe but between the latter andthe booster end of the cylinderA and adapted to communicate at its otherend with'an exhaust; and a check valve in said relief pipe and arrangedto permit fluid to flow from the booster end of said auxiliary cylinderto said 'exhaust `when said piston has travelled past the reliefpressing stroke of the ram.

5L The combinationl with a hydraulic press including a main cylinder, areciprocatory pipe during a ram therein, an auxiliary cylinder havingbooster and retracting ends, and a piston` therein and having connectionwith said ram; of a surge tank; ya high pressure pump;

means forming' a high 'pressure hydraulic circuit with said surge tank,said main cyllnder and sa1d pump and aflordmg constant commun1cat1onbetween sa1d mam cylinder and said pump; a low pressure pump; meansforming a low pressure hydrauhc circuit with both ends of said auxiliarycylinder and said low pressure pump; valve means interposed in said highand low pressure circuits and normally affording communication betweensaid surgetank and said main cylinder, and between the retracting endNof said auxiliary cylinder and said low pressure pump, said means beingmovable to first direct low pressure pump fluid to the booster end ofsaid 'auxiliary cylinder and to afford communication between theretracting end of* said auxiliary cylinder and said surge tank tothereby initiate ma pressing stroke of said ram, to then cut oilcommunication between said main cylinder and said surge tank. tocomplete the ressing stroke, and to then place said hig ,pressurecylinder'and the booster end of said auxiliary cylinder in 'meansforming a high pressure hy ram; of a surge tank; a high pressure (pumrau ic circuit with said surge tank, said mam cylinderand said pump; alow pressure pump; means forming a low pressure hydraulic circuit withboth ends of said auxiliary cylin- "der and said low pressure pump; asurge shifting valve in said high pressure circuit normally in an openposition affording communication between said main cylinder and saidsurge ltank, and movable to cut oif communicatlon therebetween; valveopening means normally maintaining said surge shifting valve in its openposition; pressure responsive means in said low pressure circuit andoperable upon a building upl of pressure therein during a pressingstroke of the ram to move said surge shifting valve to its closedposition to complete the pressing stroke; a

control valve interposed in .said high andlow,

for reversing the -ilow of fluid in saidlow pressure cncult, and meansconnected to said surge valve and'being responsive to .pressure lpressure circuits for rst directing low presl sure fluid to one end ofsaid auxiliary cyhnder to initiate the pressing stroke of the ram, andfor then directing low pressure iuid to the other end of said auxiliarycylinder or effecting a return stroke of the ram; and means forrelieving the pressure in .said auxiliary cylinder when the pistontherein has reached a predetermined point during the pressing stroke" tothereby permit said valve opening means to return the surge shiftingvalve to its open' position.

7 The c-ombinationvwith a hydraulic press including a main cylinder, areciprocatory ram therein, and auxiliary hydraulically operated meansfor operating said ram in both directions; of -a-surge tank; a source ofhigh pressure Huid pressure; means forming a high pressure hydrauliccircuit with sald high pressure source, sald `surge tank and saidmaincylinder; a sourc'e of low pressure iiuid pressure; means forming areversible flow low pressure hydraulic circuit with saidl low pressuresource and said auxiliary means for operating the latter; and means insaid low pressure clrcuit for relieving the v'pressure in both of saidcircuits when said.

ram has tr'avelled a predetermined distance while performing a pressingstroke.

8. The combination with a hydraulic press including a main cylinder, areciprocatory ram therein, an auxiliary cylinder, and a pis'- tontherein and having connectionwith said ram; a high pressure/pump; asurge tank;

means forming a high pressure circuit with sald pump; sad mam cylmdcr,and sald ltank and including neans providing constant communicationbetween the discharge side vof said pump and said main cylinder; a lowpressure pump, means connecting said low pressure pump to both ends ofsaid auxiliary cylinder to form a low pressure reversible How hydrauliccircuit; a' normally open surge valve for controlling communicationbetween said surge tank and said main cylinder means

